2-Pyrrolidone was identified by the US Department of Energy as an important C4 “Top Value-Added Chemical from Biomass” that can potentially be derived from glutamate (T. Werpy 2004). 2-Pyrrolidone is currently used as precursor for the production of N-vinylpyrrolidone, a solvent for animal injection, a building block for active pharmaceutical ingredients, optical co-solvent for water-based ink formulation, process solvent for membrane filters and a copolymer for floor polish (BASF 2015). Potential applications include ring-opening polymerization of 2-pyrrolidone to form nylon-4, a fiber material with better thermal stability and the highest hydrophilicity in the nylon family of materials (Park, Kim et al. 2013). With a variety of applications, 2-pyrrolidone continues to be a product of huge commercial interest.
Current industrial production of 2-pyrrolidone involves the dehydrogenation of 1,4-butanediol (˜$1,800-$2,000/ton) to form γ-butyrolactone on a copper catalyst (180-240° C.), followed by reacting aqueous γ-butyrolactone with ammonia on a magnesium silicate catalyst (250-290° C., 0.4-1.4 MPa) (FIG. 1A) (Albrecht Ludwig Harreus 2011). By using low cost glutamate ($900/ton) as starting material, as well as avoiding expensive catalysts and harsh reaction conditions, biological production of 2-pyrrolidone offers the potential for a cheaper and more environmentally friendly synthesis route. The ability to crystalize 2-pyrrolidone monohydrate at around 30° C. has the potential to enable low-cost separation of 2-pyrrolidone from fermentation media (Lohr 1958, Päivi Piriläa 1999).